Kinetics of the reaction between titanium(III) and vanadium(V)
- 1 January 1973
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 23,p. 2553-2557
- https://doi.org/10.1039/dt9730002553
Abstract
The kinetics of the one-equivalent reaction between titanium (III) and vanadium(V), TiIII+ VV→ TiIV+ VIV, have been studied bystopped-flow spectrophotometry. The rate is independent of chloride-ion concentration over the range up to 0·5M investigated (replacement of perchlorate by chloride). Subsequently hydrochloric acid reactant solutions adjusted to I= 0·5M with NaCl were used, therby avoiding the use of titanium(III) in perchlorate solutions. At temperatures 2·6–35° and with hydrogen-ion concentrations in the range 0·04–0·49M the rate law (i) gives a satisfactory fit to the experimental data. At 25°, k0=(7·8 ± 0·5)× 103| mol–1 s–1 and –d[VV]//dt =(k0+k–1[H+]–1)TiIII[VV](i)k–1=(8·3 ± 0·4)× 102 s–1 and activation parameters are ΔH‡ 0= 7·2 ± 0·2 kcal mol–1, ΔS‡ 0=–16·6 ± 0·8 cal K–1 mol–1, ΔH‡ -1= 14·7 ± 0·3 kcal mol–1, and ΔS‡ –1= 4·1 ± 1·1 cal K–1 mol–1. With the titanium(III) reactant in an excess a much slower second stage involving titanium(III) reduction of vanadium(IV) is observed. Use of stainless-steel syringe needles resulted in serious contamination of reactant solutions, and it was necessary to use Teflon needles at all times.Keywords
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